Biphenyl pyrazine compounds

A compound having the formula:

• ##STR26## wherein n is 1 or 3, with the proviso that A) where n is 1,
• R.sub.1 and R.sub.7 are each independently selected from the group consisting of H and --CH.sub.2 --C.sub.6 H.sub.5
• R.sub.2, R.sub.3, R.sub.6, and R.sub.8 are each independently selected from the group consisting of H, halogen, NO.sub.2 NH.sub.2, N.sub.2.sup..sym., SO.sub.3 H, SO.sub.3 M (where M is an alkali metal), C.sub.6 H.sub.5, --OR' where R' is C.sub.1-8, ##STR27## where R.sub.9 and R.sub.10 are each H, C.sub.1-6, COOCH.sub.3, and COOC.sub.2 H.sub.5, and Q.sub.1 is NH or O;
• ##STR28## where R.sub.11 is C.sub.1 -C.sub.6 ;
• ##STR29## where R.sub.12 and R.sub.13 are each independently selected from the group consisting of H, NO.sub.2, Cl, OCH.sub.3, CH.sub.3, COOH, COOCH.sub.3, NH.sub.2, ##STR30## with the proviso that at least one of R.sub.2, R.sub.3, R.sub.6, and R.sub.8 must be other than H;
• (B) where n is 3,
• R.sub.1 is ##STR31## and R.sub.2, R.sub.3, R.sub.6, R.sub.7, and R.sub.8 are the same as (A) above;
• C) where n is 1 or 3, R.sub.4 and R.sub.5 are each independently selected from the group consisting of H, NO.sub.2, NH.sub.2, and ##STR32## D) where n is 1 and R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, and R.sub.8 are H, R.sub.1, R.sub.7 are not H.